How do you get the key from sharpedo in Pokemon ranger shadows of almia?

You don't get a key from Sharpedo in Pokémon Ranger: Shadows of Almia. Sharpedo is a strong Pokémon that you can capture in the game, but it doesn't play a role in obtaining any keys.

Perhaps you're thinking of a different Pokémon, or a different item that Sharpedo might be associated with? If you can provide more details, I might be able to help you figure out what you're looking for.